Fan control switch in radiator.. good idea or bad?
 

OK guys, I've got an EFI car which is using the coolant temp sensor for the ECM. This ECM (Ford EEC-IV) does not control the fans. My Afco aluminum radiator has a bung for a sensor / switch 1/2 way up the side tank. Would it be a good idea to put a temp switch to control fans in the radiator? The radiator sees hot coolant when the stat opens and would then (at 185+) turn on the fans. Most temp switches are on the manifold before the stat, seemingly turning on the fans before the stat opens and the hot coolant fills the radiator. You think having the switch in the radiator would be too late? Or does it not matter? This sounds like a good question for Jody...

Ron Francis had really bitchin switch controller that you set up all the temps for on and off and does not use a sensor it uses a loose wire to check the resistance that way. It is super clean for the install.

http://www.parts123.com/parts123/yb....Z5Z5Z50000278a

Rodger

So it checks resistance through the block? And that changes with temp, huh? Interesting.

I have a SPAL switch that I like, it's simple, but I'm still in question about the placement. If it didn't work, there wouldn't be a bung in the radiator, right?

that ron francis thing is cool... but the fan only needs to come on when the return from the radiator is over a certain temp... i mean when you are on the highway and the air is rammmed thry the radiator you really dont need a fan... so the theoretically correct way of controlling a fan is to turn it on when the water leaving the radiator is over a certain setpoint...

with regards to fan controllerd id rather use the dakota digital unit that uses your engine temp gauge to supply signal.... but ideally id run it with a temp sender in the return side of the rad... (it will even controll a two speed fan)

I just had to install one in a 51 Chevy because the Iron manifold had no provisions, and I broke 2 socket wrenches trying to get the plug out of the cylinder head. The main reason I have against it is if the thermostat ever fails in the closed position, you will be screwed unless you have a manual bypass installed. Since the fans will only kick on once the thermostat opens, I would consider running a cooler thermostat to offset the delay in the fans kicking on.

All good info. Mike, good point about the cooler 'stat and the bypass. I think with the controller in the radiator it would be running the fans less at roadspeed as the radiator would cool faster than the engine and shut the fans off.

I guess I should just try it, as nobody screamed "DON'T DO IT, YOU'LL DIE IMMEDIATELY!

I'll report my findings when I save up enough money to drive the car again, but more feedback is encouraged.

Thanks!

- KO

Well, it turns out that the bung in the radiator is too small for the temp switch, so I have to move to plan B. Thanks for the replies, though!

What amperage size fans are you running? Painless has a sensor that will go into a 1/4 NPT. If your fans are 30amp or less, go to O'Reilly's and get an adjustable controller from Hayden. Also available with 1/4 NPT. I think the part number I just used was 3651.